One objective of a high performance air filter is to provide maximum particle removal from an airstream while maintaining an acceptable pressure drop between the upstream and downstream sides of the filter. It is known that longer filter life is obtained where more filter media is used per frontal area of filter surface. Filter assemblies that are provided with a pleated web of filter media may include a support in addition to the filter media, such as a screen or wire mesh. By providing a filter assembly with a pleated web of filter media, the amount of filter media per frontal surface area of the filter assembly can be increased. The support is provided to maintain the shape of and reduce deformation of the pleats during use due to the fluid pressure to which the filter assemblies are subjected.
The additional support material provides a number of disadvantages. It increases the pressure drop across the filter assembly because of the additional flow resistance caused by the support material. The complexity of the filter assembly, and its cost, are also increased by the need for support material. Many of the support materials are metallic and can include sharp edges that can increase the difficulty of installing the support materials.
As a result, a need exists for a pleated filter assembly that can maintain its working shape without the need for external support structure.